Rough terrain vehicles, such as cranes, are known to use spring applied, hydraulically released caliper brakes as a parking brake. These caliper brakes generally require the use of hydraulic fluid to create hydraulic pressure in order to release the brake.
The source of this hydraulic pressure is usually from vehicle hydraulics, since rough terrain vehicles generally include a hydraulic system. However, these vehicles tend to only have low pressure hydraulic circuits available in the area of the vehicle where these caliper brake are located.
One previous solution to this problem is the use of a very large piston with low pressure behind the piston. Since the piston is large, the area that pressure acts against is large, and the piston can generate enough force to overcome the springs. However, this is often not a viable option due to cost of materials and space constraints on the vehicle.
Another prior art solution is to use an external hydraulic assembly that acts on a mechanical device. This goal of such a device is to give the external assembly a mechanical advantage over the springs. But hydraulic assemblies used in this manner are prone to leakage and contamination as a linkage rod thereof generally has to move in three planes. This multi planar movement makes it difficult to effectively seal the rod which ineffective seal leads to corrosion, seal wear, and seal failures.
Thus, there is a need for an improved caliper brake that offers one or more improvements over the prior art.